Phosphorus
Definition and meaning of Phosphorus in chemistry.
![Phosphorus element card: symbol P, atomic number 15, atomic mass 30.974, electron configuration [Ne] 3s² 3p³, oxidation states +5 +3 -3, Nonmetal, group 15, period 3.](/assets/images/terms/phosphorus-chemical-element.webp)
Phosphorus is a highly reactive nonmetal element with the symbol P and atomic number 15. This element exists in several physical forms called allotropes, with white and red being the most common. It is absolutely essential for the growth and survival of all living organisms.
In more detail
Phosphorus sits in group 15 of the periodic table directly below nitrogen. Because it is highly reactive, you will never find pure phosphorus in nature. Instead, it occurs inside various phosphate minerals that make up the crust of the Earth.
White phosphorus is a waxy, toxic solid that catches fire spontaneously when exposed to the air. To prevent this dangerous burning, chemists must store white phosphorus safely under water. In contrast, red phosphorus is a much more stable powder that does not ignite easily.
We make red phosphorus by heating the white form to high temperatures without any oxygen. In biology, phosphorus forms the backbone of DNA and RNA molecules to store genetic codes. It is also the main part of ATP, which acts as the energy currency for cells.
Chemically, phosphorus bonds with oxygen and halogens to make acids, oxides, and other compounds. Many students incorrectly think that red and white phosphorus have the same molecular shape. However, white phosphorus consists of separate tetrahedral molecules, while red phosphorus forms long polymer chains.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | P |
| Atomic number | 15 |
| Atomic mass | 30.974 u |
| Category | Nonmetal |
| State at STP | Solid |
| Discovery year | 1669 |
Farmers use large amounts of phosphorus as a main ingredient in commercial plant fertilizers. The phosphorus in the soil stimulates rapid root development and helps crops mature much faster. This element is vital for storing and transferring chemical energy within the plant during photosynthesis. Without enough phosphorus, crops will show stunted growth and produce very low food yields.
Frequently asked questions
Why does white phosphorus glow in the dark?
White phosphorus reacts slowly with oxygen in the air at room temperature. This chemical reaction releases energy in the form of a faint green glow.
What is the biological function of phosphorus?
Phosphorus builds the sugar-phosphate backbone of genetic material in DNA and RNA. It also forms the high-energy bonds in ATP that power our cells.
How does phosphorus runoff affect aquatic environments?
Excess fertilizer runoff carries dissolved phosphate minerals into local lakes and rivers. This nutrient boost causes rapid algae growth, which depletes oxygen and harms fish.
Related terms
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